vfio: Pass an Error object to vfio_connect_container

vfio: Pass an Error object to vfio_connect_container

The error is currently simply reported in vfio_get_group. Don't
bother too much with the prefix which will be handled at upper level,
later on.

Also return an error value in case container->error is not 0 and
the container is teared down.

On vfio_spapr_remove_window failure, we also report an error whereas
it was silent before.

Signed-off-by: Eric Auger <[email protected]>
Reviewed-by: Markus Armbruster <[email protected]>
Signed-off-by: Alex Williamson <[email protected]>